It is standard practice to rinse articles such as electrical terminals or connectors which have been electroplated to remove the chemicals utilized in plating and clean the articles. The resulting rinse water is then treated to remove any residual precious metals for recovery with the remaining effluent passed through appropriate waste treatment A wide variety of mechanical and chemical processes such as dialysis and membrane filters have been tried and are in fact used to treat rinse water from plating operations. These processes work with varying degrees of success in recovery. Typically, processes require many stages of treatment with each stage removing a percentage of the precious metal or compound thereof but complete recovery, limited by the cost of energy and the chemicals used in recovery which in all events should not exceed the value of the recovered material or the cost of alternative disposition of such effluent.
The present invention has as an object the provision of a method and apparatus for recovering precious metals such as gold drag-out from plating and stripping operations in an economic and effective manner. The invention has a further object the provision of a method and apparatus for recovering essentially all of the precious metal found in the rinse water utilized in plating operations. Yet a further object is to provide a simple and compact apparatus for recovering potassium gold cyanide from rinse water in a manner leading to a highly efficient reuse of chemicals and water employed in the process.